The Emergence of Super-Swelled Lipid Bicontinuous Single-Crystals

Lipid bicontinuous cubic structures are arguably one of the most fascinating structures that lipid membranes are able to adopt. Their function in nature is far from unveiled but they are known, for example, to template the large unit cells (300 nm) of chitin that assign the structural color of butterfly wings. However, in the lab, lipid bicontinuous unit cells do not typically exceed 10-20 nm. We will discuss how processing of charged ternary systems out-of-equilibrium leads to super-swelled bicontinuous cubic phases. Unexpectedly, processing conditions also dictate mesophase ordering. X-ray and electron microscopy diffraction data reveals that lipid bicontinuous cubic phases can develop as perfect single-crystals of unit cell dimensions exceeding 60 nm.